My 2 cents worth:
I might feel different if this were a cutting edge peice of work
but how often is that the case with a masters thesis? Simply let the
student defend. If he has done no work he'll flunk, as he should. Then
simply repeat the experiments either yourself or with another, more
wisely chosen student. Then publish, with no data derived from your
previous student. Chalk up the time lost to poor management skills in
taking on the wrong student, or to whatever reason a previouly good
student went bad.
The above assumes you discuss the problems your having with your
student and indeed offer to write up the data with him as a co-author.
BAH